Bug 951793 - Store the overscroll behavior in ScrollMetadata and propagate it to APZ. r=mstange

MozReview-Commit-ID: J7Vkd941QxK

gfx/layers/FrameMetrics.cpp

@@ -6,6 +6,7 @@
 
 #include "FrameMetrics.h"
 #include "gfxPrefs.h"
+#include "nsStyleConsts.h"
 
 namespace mozilla {
 namespace layers {
@@ -18,6 +19,31 @@ ScrollMetadata::SetUsesContainerScrolling(bool aValue) {
   mUsesContainerScrolling = aValue;
 }
 
+static OverscrollBehavior
+ToOverscrollBehavior(StyleOverscrollBehavior aBehavior)
+{
+  switch (aBehavior) {
+  case StyleOverscrollBehavior::Auto:
+    return OverscrollBehavior::Auto;
+  case StyleOverscrollBehavior::Contain:
+    return OverscrollBehavior::Contain;
+  case StyleOverscrollBehavior::None:
+    return OverscrollBehavior::None;
+  }
+  MOZ_ASSERT_UNREACHABLE("Invalid overscroll behavior");
+  return OverscrollBehavior::Auto;
+}
+
+OverscrollBehaviorInfo
+OverscrollBehaviorInfo::FromStyleConstants(StyleOverscrollBehavior aBehaviorX,
+                                           StyleOverscrollBehavior aBehaviorY)
+{
+  OverscrollBehaviorInfo result;
+  result.mBehaviorX = ToOverscrollBehavior(aBehaviorX);
+  result.mBehaviorY = ToOverscrollBehavior(aBehaviorY);
+  return result;
+}
+
 StaticAutoPtr<const ScrollMetadata> ScrollMetadata::sNullMetadata;
 
 }

gfx/layers/FrameMetrics.h

@@ -721,6 +721,32 @@ struct ScrollSnapInfo {
   nsTArray<nsPoint> mScrollSnapCoordinates;
 };
 
+MOZ_DEFINE_ENUM_CLASS_WITH_BASE(
+  OverscrollBehavior, uint8_t, (
+    Auto,
+    Contain,
+    None
+));
+
+struct OverscrollBehaviorInfo {
+  OverscrollBehaviorInfo()
+    : mBehaviorX(OverscrollBehavior::Auto)
+    , mBehaviorY(OverscrollBehavior::Auto)
+  {}
+
+  // Construct from StyleOverscrollBehavior values.
+  static OverscrollBehaviorInfo FromStyleConstants(StyleOverscrollBehavior aBehaviorX,
+                                                   StyleOverscrollBehavior aBehaviorY);
+
+  bool operator==(const OverscrollBehaviorInfo& aOther) const {
+    return mBehaviorX == aOther.mBehaviorX &&
+           mBehaviorY == aOther.mBehaviorY;
+  }
+
+  OverscrollBehavior mBehaviorX;
+  OverscrollBehavior mBehaviorY;
+};
+
 /**
  * A clip that applies to a layer, that may be scrolled by some of the
  * scroll frames associated with the layer.
@@ -797,6 +823,7 @@ public:
     , mIsLayersIdRoot(false)
     , mUsesContainerScrolling(false)
     , mForceDisableApz(false)
+    , mOverscrollBehavior()
   {}
 
   bool operator==(const ScrollMetadata& aOther) const
@@ -813,7 +840,8 @@ public:
            mAllowVerticalScrollWithWheel == aOther.mAllowVerticalScrollWithWheel &&
            mIsLayersIdRoot == aOther.mIsLayersIdRoot &&
            mUsesContainerScrolling == aOther.mUsesContainerScrolling &&
-           mForceDisableApz == aOther.mForceDisableApz;
+           mForceDisableApz == aOther.mForceDisableApz &&
+           mOverscrollBehavior == aOther.mOverscrollBehavior;
   }
 
   bool operator!=(const ScrollMetadata& aOther) const
@@ -923,6 +951,13 @@ public:
     return mForceDisableApz;
   }
 
+  void SetOverscrollBehavior(const OverscrollBehaviorInfo& aOverscrollBehavior) {
+    mOverscrollBehavior = aOverscrollBehavior;
+  }
+  const OverscrollBehaviorInfo& GetOverscrollBehavior() const {
+    return mOverscrollBehavior;
+  }
+
 private:
   FrameMetrics mMetrics;
 
@@ -972,6 +1007,9 @@ private:
   // scrollframe.
   bool mForceDisableApz:1;
 
+  // The overscroll behavior for this scroll frame.
+  OverscrollBehaviorInfo mOverscrollBehavior;
+
   // WARNING!!!!
   //
   // When adding new fields to ScrollMetadata, the following places should be

gfx/layers/apz/src/AsyncPanZoomController.cpp

@@ -3859,6 +3859,7 @@ void AsyncPanZoomController::NotifyLayersUpdated(const ScrollMetadata& aScrollMe
     mScrollMetadata.SetUsesContainerScrolling(aScrollMetadata.UsesContainerScrolling());
     mFrameMetrics.SetIsScrollInfoLayer(aLayerMetrics.IsScrollInfoLayer());
     mScrollMetadata.SetForceDisableApz(aScrollMetadata.IsApzForceDisabled());
+    mScrollMetadata.SetOverscrollBehavior(aScrollMetadata.GetOverscrollBehavior());
 
     if (scrollOffsetUpdated) {
       APZC_LOG("%p updating scroll offset from %s to %s\n", this,

gfx/layers/ipc/LayersMessageUtils.h

@@ -78,6 +78,14 @@ struct ParamTraits<mozilla::layers::FrameMetrics::ScrollOffsetUpdateType>
              mozilla::layers::FrameMetrics::sHighestScrollOffsetUpdateType>
 {};
 
+template <>
+struct ParamTraits<mozilla::layers::OverscrollBehavior>
+  : public ContiguousEnumSerializerInclusive<
+            mozilla::layers::OverscrollBehavior,
+            mozilla::layers::OverscrollBehavior::Auto,
+            mozilla::layers::kHighestOverscrollBehavior>
+{};
+
 template<>
 struct ParamTraits<mozilla::layers::LayerHandle>
 {
@@ -224,6 +232,27 @@ struct ParamTraits<mozilla::layers::ScrollSnapInfo>
   }
 };
 
+template <>
+struct ParamTraits<mozilla::layers::OverscrollBehaviorInfo>
+{
+  // Not using PlainOldDataSerializer so we get enum validation
+  // for the members.
+
+  typedef mozilla::layers::OverscrollBehaviorInfo paramType;
+
+  static void Write(Message* aMsg, const paramType& aParam)
+  {
+    WriteParam(aMsg, aParam.mBehaviorX);
+    WriteParam(aMsg, aParam.mBehaviorY);
+  }
+
+  static bool Read(const Message* aMsg, PickleIterator* aIter, paramType* aResult)
+  {
+    return (ReadParam(aMsg, aIter, &aResult->mBehaviorX) &&
+            ReadParam(aMsg, aIter, &aResult->mBehaviorY));
+  }
+};
+
 template <>
 struct ParamTraits<mozilla::layers::LayerClip>
 {
@@ -263,6 +292,7 @@ struct ParamTraits<mozilla::layers::ScrollMetadata>
     WriteParam(aMsg, aParam.mIsLayersIdRoot);
     WriteParam(aMsg, aParam.mUsesContainerScrolling);
     WriteParam(aMsg, aParam.mForceDisableApz);
+    WriteParam(aMsg, aParam.mOverscrollBehavior);
   }
 
   static bool ReadContentDescription(const Message* aMsg, PickleIterator* aIter, paramType* aResult)
@@ -289,7 +319,8 @@ struct ParamTraits<mozilla::layers::ScrollMetadata>
             ReadBoolForBitfield(aMsg, aIter, aResult, &paramType::SetAllowVerticalScrollWithWheel) &&
             ReadBoolForBitfield(aMsg, aIter, aResult, &paramType::SetIsLayersIdRoot) &&
             ReadBoolForBitfield(aMsg, aIter, aResult, &paramType::SetUsesContainerScrolling) &&
-            ReadBoolForBitfield(aMsg, aIter, aResult, &paramType::SetForceDisableApz));
+            ReadBoolForBitfield(aMsg, aIter, aResult, &paramType::SetForceDisableApz) &&
+            ReadParam(aMsg, aIter, &aResult->mOverscrollBehavior));
   }
 };
 

ipc/glue/IPCMessageUtils.h

@@ -256,6 +256,11 @@ struct BitFlagsEnumSerializer
  * structure's members.
  *
  * Derive ParamTraits<T> from PlainOldDataSerializer<T> if T is POD.
+ *
+ * Note: For POD structures with enumeration fields, this will not do
+ *   validation of the enum values the way serializing the fields
+ *   individually would. Prefer serializing the fields individually
+ *   in such cases.
  */
 template <typename T>
 struct PlainOldDataSerializer

layout/base/nsLayoutUtils.cpp

@@ -9357,6 +9357,11 @@ nsLayoutUtils::ComputeScrollMetadata(nsIFrame* aForFrame,
     metadata.SetUsesContainerScrolling(scrollableFrame->UsesContainerScrolling());
 
     metadata.SetSnapInfo(scrollableFrame->GetScrollSnapInfo());
+
+    ScrollbarStyles scrollbarStyles = scrollableFrame->GetScrollbarStyles();
+    metadata.SetOverscrollBehavior(OverscrollBehaviorInfo::FromStyleConstants(
+        scrollbarStyles.mOverscrollBehaviorX,
+        scrollbarStyles.mOverscrollBehaviorY));
   }
 
   // If we have the scrollparent being the same as the scroll id, the